The additional brake is an important safety device of escalator, when the drive chain of the escalator falls off or breaks accidentally, the additional brake can carry out emergency braking, it can make the escalator slow down and stop effectively, prevent sudden stop and reverse and protect the passenger’s personal safety.
Whether additional brakes are required for escalators? The regulations TSG T7005 — 2012 “elevator supervision and periodic inspection rules — escalator and automatic sidewalk” require additional brakes to be installed when the working brake and step drive device of escalator are not connected by shaft, gear, multi-row chain or multi-row chain.
Recently, inspectors found that the escalator of a brand of regular inspection, the use of the longer period, the production date was on 1996. According to the inspection rules, when the working brake of escalator is not connected with a multi-row chain or a single-row chain, additional brake must be installed. Therefore, the escalator does not meet the requirements, so it shall be rectified.
First, the requirements for additional brakes: The additional brake shall be connected with the step chain by a shaft, gear or multi-row chain and shall be mechanical and brake by friction principle. Thus, it should be able to directly stop the drive wheel, and the way to stop should be direct, not through the indirect way to achieve, such as belt
Secondly, under the action of braking force, additional brakes are required to effectively slow down and stop an escalator running downward with brake loads. This means that additional brakes can reliably stop the escalator’s drive wheel, rather than just applying force to the parts associated with the drive wheel, such as the drive shaft, and should produce enough force to stop it completely.
Finally, the additional brakes should be forced to cut off the control circuit at the start of the action and work in any of the following situations: over speed, before the nominal speed exceeds 1.4 times, and retrograde (when the steps change the specified direction of operation). There is a requirement to disconnect the safety circuit, that is, the added device should have electrical considerations and be able to detect the speed of the escalator. Generally speaking, the speed measurement system of the additional brake should be a programmable electronic system related to safety, which should meet the requirement of SIL2 and should be tested and verified.
From what has been discussed above, adding a set of devices to make it conform to the above points can meet the requirements of relevant standards and regulations. For the escalator, the existing truss space of the escalator and the existing drive chain breaking protection system can be utilized to add a set of devices to realize the function of additional brake.